He
was born in 1588 and
was baptised with the name of Alexander Seton, the 3rd son of Robert Seton, 8th
Lord Seton and 1st Earl of Winton and his wife Lady Margaret Montgomerie, and a
grandson of the famed George, 7th Lord Seton. He was
born and raised at Seton Palace, with the strong hereditary military training of the Seton's, which benefited
him greatly in his career's later years. Nicknamed 'Greysteel', he
continued the distinguished family traditions, becoming a Privy Councillor and
carrying the spurs at the Royal Coronation of King Charles I.

His
father was a
great favorite with the King,
and exercised great
hospitality at Seton where he frequently entertained James VI and his Queen, and
noted that, “he was very hospitable, and kept a noble house, the
King
and Queen being frequently there, and all French and other ambassadors and
strangers of quality were nobly entertained.” The list of Grand Balls and
Masques would fill volumes; the great entertaining traditions he elaborated on
from his father and grandfather, were passed to his own sons and heirs.

In his early years, he was granted the
Estate of Foulstruther near to Pencaitland as his patrimony,
and he showed great promise in service to the Royal House,
and was knighted early in life. Given the events of the
time, he was engaged into a dispute carrying on from the
famed riot in Edinburgh betwen the Seton's and Cunningham's,
and on the 2nd of July, 1606, he and his elder brother
George Seton (later third earl of Winton), were summoned to
appear before the Privy Council to answer for an attack on
James Cunningham, 7th Earl of Glencairn, at Perth. The
matter was eventually settled on the 23rd of December, when
the 'Master' and Glencairn both received an order to
subscribe to an assurance.

When Hugh, the fifth earl of Eglinton, died childless and
estranged from his wife, he made a resignation and
settlement of the Earldom of Eglinton and it's entail on his
lineal cousins, the younger sons of Lady Margaret
Montgomerie, and to her younger children, 1st Alexander, 2nd
Thomas, and 3rd John, and to each of them successively and
to their heirs male, with the added provision that the
Seton-heir would take and continue the Arms and name of
Montgomery.

The settlement was confirmed by a
Charter under the Great Seal on 28 November 1611, and the
newly made Earl rapidly acquired a wife. On 22 June 1612
Alexander married Anna Livingstone (d. 1632), eldest
daughter of Alexander Livingstone, first Earl of Linlithgow.
The couple had five sons and three daughters: Hugh
Montgomery, the future seventh Earl of Eglinton, and Robert
Montgomery were the eldest and the youngest sons.

Within five months of his marriage Alexander had succeeded
his cousin as earl of Eglinton after Hugh Montgomerie died
on 4 September 1612 and Alexander was infeft in the earldom
on 30 October.

The succession was not without
controversy, and the 'favourite', the Duke of Buckingham
raised much opposition and appealed to the King. King
James hotly challenged the transference of the title as
having occurred without his authority, and personally
objected and intervened. On 28 April 1613 the privy council
decided Seton should be cited to appear on 18 May, to ‘hear
and see him discharged of all assuming unto himself the
style, title, and name of earl’. And although he initially
refused to do so, he ultimately on 15 March 1615 he appeared
before the council, apologized for having used the title
without the king's permission, and resigned it to the king.

Consequently James, by the previous
arrangement, conferred the earldom of Eglinton on Seton,
under the designation Alexander Montgomerie, earl of
Eglinton, Lord Montgomerie and Kilwinning. It was only through the negotiation
and the influence of his powerful uncle Alexander Seton, 1st Earl of Dunfermline and Chancellor of Scotland
and his influence with her
Majesty Queen Anne, that Sir Alexander Seton of Foulstruther
was able to become the 6th Earl of Eglinton.

Tradition states that King James
finally agreed owing to the plea of his favourite, Robert
Carr, Earl of Somerset, after Eglinton had told him that,
though ignorant of the intricacies of the law he knew the
use of the sword, and had intimated that he would challenge
the favourite to a duel unless the opposition to his
assumption of the title was withdrawn. From the incident
Eglinton, who was a very skilful swordsman, received the
nickname ‘Greysteel’.

However, the
also arrangement precluded that he and his heirs take the
name of Montgomerie and for that family line to continue, and
to no longer
to be known as 'Seton', in order that he be adopted into the family and
House of Montgomerie. He
thus succeeded on 4th September, 1612, by Right of his
mother and became the 6th Earl of Eglinton and took the name
of Montgomerie; becoming Alexander Montgomerie. As a
result of the succession process, on 24th March, 1615, he
resigned his titles and had a re-grant from King James VI
and I, whereupon he obtained the Royal Grants and
Confirmations of the Estates and Honours of Montgomerie.

Meanwhile in 1614 the new earl had
entered into a feud with the archbishop of Glasgow over the
patronage and teinds of eight parishes, which lasted until
1621. In assuming control of the earldom, Alexander had to
buy-back the lordship of Kilwinning at a hefty price from
Lord Balfour of Burleigh, for 8000 merks. In 1617 King James
visited Eglinton during his Scottish tour. In alliance with
the earl of Rothes, Eglinton opposed the introduction of the
five articles of Perth in 1617–21, and at the parliament of
1621 he was one of the commissioners who voted against them.
Yet despite his dissent from Royal policy, Eglinton was one
of the Scots nobles who on 7 May 1625 attended the funeral
of King James in Westminster Abbey. He also formed one of
the procession of the state entry of King Charles into
Edinburgh on 15 June 1633; and at the coronation on 18 June
he carried the spurs; at the rising of the parliament on 24
June he carried the sword.

As his opposition to the five articles
indicates, despite an upbringing and an early adulthood as a
Roman Catholic, Eglinton became one of the first staunch
Presbyterian nobles, chiefly through the influence of David
Dickson (or Dick), minister of Irvine from 1618 to 1640,
whom he affirmed was ‘the instrument to reclaim him from
popery’, the traditional faith of the Setons. At Eglinton
Castle, the Earl kept an elaborate estate, and after Dickson
was deprived of his ministry at Irvine for publicly
protesting against the articles, the earl obtained his
liberty and invited him with full hospitality ‘to come to
Eglinton and to visit..., but not to preach there’. Yet on
Dickson's arrival he arranged that he should preach in the
hall of the castle, and afterwards in the close when the
crowd who gathered to hear him became too large for the
hall. And although after two months he was ordered to
proceed to prison, Eglinton gained consent for the
minister's return to Irvine.

Countess Anna shared her husband's
presbyterian commitment, and was a patroness of godly
ministers. ‘I sie clearlie the Lord hes appointed yow to be
a wessel of honore. This is the crosse of Christ that is
upon your ladyship and it will sanctifie the domestick’,
Robert Bruce of Kinnaird assured her, while from Temple
Patrick, co. Antrim, the presbyterian minister Josias Welsh
addressed her as ‘elect ladye’.

Eglinton's commitment to Presbyterianism remained strong
owing to his conversations with Robert Baillie, minister of
Kilwinning (1631–42). After the riot at St Giles's Church,
Edinburgh, against the introduction of the new prayer book
in July 1637, Eglinton joined other nobles in a petition
condemning the offending book and took an active part in the
plans for the preparation of the national covenant, acting
as a witness to the oaths of those subscribing to it in
March 1638. He also enlisted William Keith, sixth Earl
Marischal, the husband of his niece, Lady Elizabeth Seton,
to the cause. As an elder commissioner from the presbytery
of Glasgow he attended the general assembly of 1638. There
he served on the committee appointed for receiving
complaints against the bishops.

In May 1639 the Tables appointed he and John Kennedy, sixth
earl of Cassillis, to defend Galloway and Ayrshire against
Lord Wentworth's Irish army. Summoned to join Lord General
Alexander Leslie's army at Duns Law, Berwickshire, Eglinton
‘came away with the whole country at his back’, bringing
1000 foot soldiers, and mounted men including 100 gentry and
200 tenants. In April 1640 the convention of estates
deputeed he and Archibald Campbell the Earl of Argyll, to
protect the western parts of Scotland from the landing of
Irish forces, with Eglinton taking responsibility for the
lands south of the Clyde. On the 29th of August, Argyll
ordered him to gather boats and ships at Ayr as part of the
defensive measures.

After the treaty of London between the
King and the Covenanters, he was nominated to the Scottish
Privy Council on 17 September 1641, and parliament confirmed
his selection on 13 November. He was also one of the
committee appointed to inquire into ‘the incident’, the plot
against Argyll, Hamilton, and Lanark. In the aftermath of
the Ulster rising by the Irish Roman Catholics in October
1641 the earl sent officers from his former regiment to the
province to train the foot regiment of Lord Montgomery of
the Ards. On 11 March 1642 the privy council commissioned
Eglinton as a colonel of foot from the southern lowlands in
the army paid for by the English to suppress the Irish
rising. The earl accepted the charge four days later.

The regiment of 1116 officers and men
in ten companies reached Ulster in May. The earl only
accompanied the regiment between 4 August and November. On
28 February 1643 he contributed £6000 to the voluntary loan
for the supply of the army. In March 1644 he lost the
Coloneletcy to his Lieutenant-Colonel, James Montgomery.
Meanwhile on 5 July 1642 the privy council named him to the
Ayrshire commission for the apprehension of Roman Catholics.
On 3 March 1643 it appointed Eglinton one of the
conservators of peace, a joint Anglo-Scottish body for the
maintenance of the treaty of London.

In autumn 1643 the convention of estates appointed Eglinton
colonel of horse for the shires of Ayr, Renfrew, and Lanark
in the army being raised to assist the English
parliamentarians against the king. The regiment entered
England on 19 January 1644 in the earl of Leven's army. By
some time in February the earl and his officers had levied
all the regiment's eight troops. Eglinton was present at the
siege of York in April–June; he entered the city during one
assault with 4000 Scots, and helped to repulse bloodily a
sally by the defenders. At the battle of Marston Moor on 2
July his regiment served as the reserve of Fairfax's cavalry
on the right wing.

Following the destruction of the
parliamentarian horsemen, Eglinton and his officers kept the
regiment in place, anchoring the right of the allied line.
Shortly afterwards he returned to Scotland, and attended the
parliament that met on 28 July. Some time in 1645 the
colonelcy of Eglinton's cavalry regiment passed to his son,
Lieutenant-Colonel Robert Montgomery. After the covenanter
debacle at Kilsyth on 15 August 1645 he raised levies to
oppose the royalists, but they fled on the approach of
Alasdair MacColla. Later that year he was one of the
committee of estates appointed to consider the petition of
General William Baillie for a trial over his conduct at the
battle of Kilsyth. On 30 January 1646 he was named one of
the committee of estates.

In 1648 Eglinton strongly disapproved of the engagement to
march an army into England for the relief of the king. In
March he fought a duel over the matter with William
Cunningham, eighth earl of Glencairn. In late May at Irvine
he joined with other kirk party leaders to discuss a rising
against the engagers, but abandoned the idea. When word of
the engagers' defeats in the north-west of England reached
Ayrshire in late August, his son Robert raised a force of
Ayrshire who started the whiggamore raid by attacking a
troop of the earl of Lanark's horse. Eglinton joined with
John Campbell, first earl of Loudoun, in raising 6000 men
from Kyle, Cunningham, Renfrewshire, and Lanarkshire. He
also took Edinburgh Castle on 5 September, then marched
north to Falkirk on 12 September. Following the engager
surrender the earl led his men home on 29 September. In
January 1649 he attended the kirk-party-dominated parliament
as one of only sixteen nobles.

On news of the execution of Charles I,
he supported the proposal for the recall of Charles II as a
‘covenanted king’. On 22 July 1650, following the king's
arrival in Scotland, the estates appointed Eglinton colonel
of his majesty's Life Guard of Horse. Previously, on 28
June, he had been named to the purging committee (to free
the army of royalists and openly sinful soldiers). Yet
despite his staunch commitment to the kirk party, the earl
does not seem to have paid much attention to the quality of
his new recruits, and while the regiment quickly reached
full strength, its reputation for indiscipline became
renowned.

On 29 July the king came from Stirling
to the army's camp at Leith on the earl's urging. At
Dunfermline on 13 August Eglinton attended the first council
held by the king since his arrival in Scotland. After the
defeat at Dunbar on 3 September, the earl returned to
Ayrshire and levied reinforcements for the army, but he
refused to serve under the radical Colonel Gilbert Ker and
disbanded most of his men; nevertheless 146 of his cavalry
recruits had joined his son (now Major-General) Robert
Montgomery's horse by December. In early October, when the
king tried to join the royalists in the north of Scotland,
Eglinton joined with other nobles in Perth and sent him a
polite letter asking him to return. Eglinton joined Argyll
and other members of the moderate kirk party in opposing the
extreme covenanters of the south-west. He proposed that the
western remonstrance be condemned as treasonable and
scandalous, and be burnt by the public hangman. In his
appointment with Argyll and Loudoun to persuade the
remonstrant lairds to agree to a union of forces, however,
were met with no success.

In
spring 1651 Eglinton raised troops for the king but while in
Dumbarton with his son Colonel James Montgomery of
Coilsfield, Ayrshire, English soldiers captured them in
their beds. For betraying them one Archibald Hamilton was
hanged at Stirling in April 1651. Eglinton and his son were
taken first to Edinburgh Castle, then to Hull, and finally
to Berwick. While a prisoner Eglinton was widowed a second
time. Some ten years after the death of his first wife on 11
November 1632 he had married Margaret Scott, eldest daughter
of Walter Scott, first Lord Scott of Buccleuch, and widow of
James Ross, lord of Buccleuch (the marriage took place
between November 1642 and March 1644). The flavour of her
rigorous piety is caught by a letter to her husband
commending his action in sacking a female servant whose
misbehaviour was suspected but not proved in which she
expressed the wish that ‘God Almighti send a gud tryell of
all the wichtis, and send them a hotte fire to burne them
with’. She died at Hull on 3 October 1651. On 15 October
1652 he received the liberty of the town of Berwick.

Despite his
status, he fell into the hands of the Protector, Oliver
Cromwell, who imprisoned him between 1651 and 1660, and which
declined his health.

While his subsequently having his
liberty was increased for a time, on the 18th of July 1654
the Governor of Berwick was ordered to secure he and his
eldest son, Hugh, Viscount Montgomerie, until they produced
Robert Montgomery and handed him over to the English, or
until they gave security that he would leave the
Commonwealth. Although his heir the Viscount was excluded
from the Act of Grace and Pardon, the Earl himself was
included and his estates returned to him after two years'
sequestration. However, in August 1659, General George Monck
had him imprisoned yet again to prevent him from rebelling
in favour of the king. He was freed by December 1659, when
the Scottish shire commissioners at Berwick selected him as
one of five direct negotiators with Monck, and while he
lived to see the restoration of the king, he unfortunately
did not live to see that of Episcopacy, and he died at
Eglinton Castle on 7 January 1661, and was buried at his
Parish Kirk in Kilwinning on the 14th of February.

For the terms of his succession, on the
Viscount's marriage in 1631, he had settled the estates on
his son and heir, reserving for himself only a life-rent,
and where in turn the Viscount-heir promised not to
interfere with the estates during his father's lifetime, and
those not having being forfeit, settled them likewise 1655
on the Viscount's own eldest son and heir, Alexander
Montgomerie; and
his son Hugh Montgomerie, succeeded him at his death as 7th Earl of Eglinton, in 1661.

Sir Alexander was married
firstly to Lady Anne Livingstone, daughter of Alexander
Livingstone, 1st Earl of Linlithgow and Lady Helen Hay, on
22 June 1612. He married secondly, Lady Margaret Scott, daughter
of Sir Walter Scott, 1st Lord Scott of Buccleuch and Mary
Ker, between November 1642 and March 1644.

The
titular-representation of the Seton family of Winton:
The senior and legitimate male line of the House of Seton devolved upon
the Earl's of Eglinton, in consequence of the marriage in
1582 of Robert the first Earl of Winton with Lady Margaret
Montgomerie, eldest daughter of Hugh third Earl of Eglinton,
to the male-line of the Seton's which had become merged in that of the
Earl's of Eglinton. With the extinction of the legitimate
Seton male-heirs-decent of the 3rd and 4th Earl's of Winton
and the succession falling to the male-line of Robert, 1st
Earl of Winton (the 2nd Earl passed the Honours to his
brother George, who became 3r Earl of Winton), the present Earl
of Eglinton is the lineal heir-male of the body of The Hon. Sir
Alexander Seton, 6th Earl of Eglinton's line, and in consequence of
the failure of the direct Winton line and of all the male
descendants of George, 3rd Earl of Winton, Lord Eglinton is
the accepted legal lineal-titular-male representative of
Honours of the family of Seton.

However, it
would be important to note that having not reciprocated in
the original terms of the Winton succession, and that of
Montgomerie's own example; in passing of the Winton-title's
and Honours to the senior son of the house and he
assuming the Arms and name of Seton, forsaking that of
Montgomerie, as outlined in the Royal regrant of the Winton
Honours by George, 4t Earl of Winton and that also of George
3rd Earl of Winton, the Eglinton-Montgomerie's are therefore
not considered by the Seton family to be Head of the House
of Seton, nor of the Name, and have simply succeeded to the
Titles, and inappropriately so.